Differential Diagnosis for Red Painful Elbows and Knees with Swelling in a 68-year-old Female

Single Most Likely Diagnosis

• Osteoarthritis (OA) with inflammatory flare: This is a common condition in elderly individuals, characterized by joint pain, swelling, and stiffness. The presence of redness and swelling could indicate an inflammatory component or a flare of OA.
• Gout: Although more common in men, gout can occur in postmenopausal women. It presents with sudden onset of joint pain, redness, and swelling, often affecting the lower extremities but can also involve elbows.

Other Likely Diagnoses

• Rheumatoid Arthritis (RA): An autoimmune disorder that can cause symmetric joint pain, swelling, and stiffness, particularly in the hands and feet but can also affect elbows and knees. It's more common in women.
• Psoriatic Arthritis (PsA): A condition that combines the swollen, scaly skin of psoriasis with joint pain and arthritis. It can cause red, swollen joints and is often accompanied by psoriatic skin lesions.
• Septic Arthritis: Although less common, any joint can become infected, leading to septic arthritis, which presents with sudden onset of pain, swelling, and redness in a single joint, often accompanied by systemic symptoms like fever.

Do Not Miss Diagnoses

• Crystal Arthropathy (Gout or Pseudogout): These conditions can present with acute, severe joint pain and swelling. Missing the diagnosis could lead to inadequate treatment and potential long-term joint damage.
• Infectious Arthritis: Failing to diagnose and treat infectious arthritis promptly can lead to severe joint destruction and systemic complications.
• Lyme Arthritis: Caused by the bacterium Borrelia burgdorferi, transmitted by ticks. It can cause arthritis that resembles OA but is treatable with antibiotics if diagnosed early.

Rare Diagnoses

• Relapsing Polychondritis: A rare autoimmune disorder that can cause cartilage inflammation, leading to joint pain and swelling, among other symptoms.
• Sarcoid Arthritis: Part of sarcoidosis, a condition where inflammatory cells form lumps known as granulomas in various parts of the body, including joints, leading to pain and swelling.
• Hemochromatosis: A genetic disorder characterized by excessive iron accumulation in the body, which can lead to arthritis, among other symptoms, due to iron deposition in joints.

Each of these diagnoses has distinct features that can guide further investigation and management. A thorough history, physical examination, laboratory tests, and sometimes imaging studies are necessary to confirm the diagnosis and initiate appropriate treatment.